What would happen to the Earth if it had two moons: would the world as we know it collapse?

Since ancient times, the Moon has been a witness and protagonist of life on Earth. This natural satellite, unique in its kind, not only beautifies our nights, but also deeply influences nature and the life cycles of the planet. However, what would happen if Earth had a second moon? Although unlikely, this is the scenario of an Earth with two of these large natural satellites, also present on other planets in the universe.

Scientists from NASA and National Geographic have explored the panorama of another luminous sphere that decorates the sky, whether larger, smaller or the same size as the current Moon. This second satellite would alter the way we experience the night, flooding the sky with more light and leading to unique visual spectacles, such as more frequent and brighter eclipses. However, due to the creation of a second Moon there would be more threats than luminous spectacles, according to the institution’s study.

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The Moon influences the tides

This natural satellite was formed about 4.5 billion years ago after a collision between Earth and a protoplanet the size of Mars and has been key to the development of life. Its orbit stabilizes the Earth’s axis of rotation, moderating the climate and allowing relatively stable seasonal cycles. In addition, its gravitational influence creates tides, a phenomenon that affects marine ecosystems, regulates the migratory patterns of many species and has historically shaped the geography of the coasts.

The gravitational influence of a second moon would significantly alter the tides. The waves could reach heights eight times greater than today, making coastal areas uninhabitable. Rivers and other water sources connected to the sea would also be affected, increasing the risk of extreme flooding and overflows.

Two moons in the sky would be a threat

If the Earth were to acquire a second moon, the visual panorama would be impressive, as completely new phenomena could be observed, such as double eclipses, overlapping shadows and much brighter nights. However, this second satellite would have profound implications for the dynamics of the Earth. The tides, controlled by the Moon’s gravitational force, would increase significantly. Depending on the distance and size of this new moon, the waves could be between two and eight times larger than today, flooding coasts, rivers and lowlands. Inhabited regions today would be deserted due to the impossibility of building infrastructure that can withstand such a scourge of water.

Additionally, the combined forces of the two moons could alter the planet’s very shape, intensifying gravitational deformations in the Earth’s crust. This could destabilize tectonic plates and increase the frequency and intensity of earthquakes and volcanic eruptions.

There would be changes in the earth cycles

The lunar cycle, which currently lasts about 29 days, would become more complex. With two moons in orbit, the months could be divided into multiple shorter cycles, which would change the way we measure time. This would have a direct impact on terrestrial and marine ecosystems, since many species depend on lunar cycles for activities such as reproduction or migration, which could destabilize these patterns, leading to the extinction of species that fail to adapt.

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In nature, nocturnal animals would have to adapt to brighter nights. Predators and prey would develop new hunting and camouflage strategies. Meanwhile, humans would have to adjust their daily lives to cope with brighter nights and days with altered cycles.

Would Two Moons be a catastrophic scenario?

Although NASA theories allow us to imagine the effects of two moons, not everything would be sustainable in the long term. According to NASA scientist Neil F. Comins, The gravitational movement of the two moons could lead them to collide. This impact would generate a rain of debris that would fall to Earth, endangering humanity and all forms of life. The final result of this catastrophe would be the formation of a new moon from the remains of both. However, by that time, the Earth would have suffered irreparable damage, possibly leading to the extinction of humanity.

In recent years, scientists have detected small objects, known as “minimoons,” temporarily orbiting the Earth. These asteroids are captured by Earth’s gravity, but remain in orbit for only a few months before escaping into space. Although they are not considered true moons, these phenomena offer valuable clues about how a celestial body could become a stable satellite. For example, the school bus-sized asteroid 2024 PT5 has been nicknamed a “mini moon” for its temporary passage through Earth’s orbit. Although its influence is negligible, its study helps astronomers better understand gravitational dynamics and develop strategies to deflect dangerous objects in the future.

The probability of our planet acquiring a second moon is extremely low. For this to happen, it would have to capture a large, stable celestial body, such as an asteroid, and keep it in orbit. Although small objects have been temporarily captured by Earth’s gravity, they have never stuck around long enough to become true natural satellites.

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